Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri 65212, USA.
Am J Physiol Gastrointest Liver Physiol. 2012 Jan 1;302(1):G44-54. doi: 10.1152/ajpgi.00413.2010. Epub 2011 Sep 15.
The objectives of this study were to determine whether neutrophil depletion with anti-neutrophil serum (ANS) or preconditioning with the hydrogen sulfide (H(2)S) donor NaHS (NaHS-PC) 24 h prior to ischemia-reperfusion (I/R) would prevent postischemic mitochondrial dysfunction in rat intestinal mucosa and, if so, whether calcium-activated, large conductance potassium (BK(Ca)) channels were involved in this protective effect. I/R was induced by 45-min occlusion of the superior mesenteric artery followed by 60-min reperfusion in rats preconditioned with NaHS (NaHS-PC) or a BK(Ca) channel activator (NS-1619-PC) 24 h earlier or treated with ANS. Mitochondrial function was assessed by measuring mitochondrial membrane potential, mitochondrial dehydrogenase function, and cytochrome c release. Mucosal myeloperoxidase (MPO) and TNF-α levels were also determined, as measures of postischemic inflammation. BK(Ca) expression in intestinal mucosa was detected by immunohistochemistry and Western blotting. I/R induced mitochondrial dysfunction and increased tissue MPO and TNF-α levels. Although mitochondrial dysfunction was attenuated by NaHS-PC or NS-1619-PC, the postischemic increases in mucosal MPO and TNF-α levels were not. The protective effect of NaHS-PC or NS-1619-PC on postischemic mitochondrial function was abolished by coincident treatment with BK(Ca) channel inhibitors. ANS prevented the I/R-induced increase in tissue MPO levels and reversed mitochondrial dysfunction. These data indicate that neutrophils play an essential role in I/R-induced mucosal mitochondrial dysfunction. In addition, NaHS-PC prevents postischemic mitochondrial dysfunction (but not inflammation) by a BK(Ca) channel-dependent mechanism.
本研究旨在确定抗中性粒细胞血清（ANS）耗竭或预先用硫化氢（H₂S）供体 NaHS（NaHS-PC）预处理 24 小时是否可防止大鼠肠黏膜缺血再灌注（I/R）后的线粒体功能障碍，如果是这样，钙激活的大电导钾（BK（Ca））通道是否参与这种保护作用。通过预先用 NaHS（NaHS-PC）或 BK（Ca）通道激活剂（NS-1619-PC）预处理 24 小时或用 ANS 处理大鼠，用 45 分钟阻断肠系膜上动脉诱导 I/R，然后再灌注 60 分钟。通过测量线粒体膜电位、线粒体脱氢酶功能和细胞色素 c 释放来评估线粒体功能。还测定了黏膜髓过氧化物酶（MPO）和 TNF-α水平，作为缺血后炎症的指标。通过免疫组织化学和 Western blot 检测肠黏膜中 BK（Ca）的表达。I/R 诱导线粒体功能障碍并增加组织 MPO 和 TNF-α水平。尽管 NaHS-PC 或 NS-1619-PC 可减轻线粒体功能障碍，但黏膜 MPO 和 TNF-α水平的缺血后增加并未减轻。BK（Ca）通道抑制剂同时治疗可消除 NaHS-PC 或 NS-1619-PC 对缺血后线粒体功能的保护作用。ANS 可防止 I/R 引起的组织 MPO 水平升高并逆转线粒体功能障碍。这些数据表明，中性粒细胞在 I/R 诱导的黏膜线粒体功能障碍中起关键作用。此外，NaHS-PC 通过依赖 BK（Ca）通道的机制防止缺血后线粒体功能障碍（但不是炎症）。
